The penetration of geological formations by rotary drilling methods requires the circulation of fluids for the removal of particulate matter. Heretofore, both liquid and air (gas) have been circulated under high pressure through the drilling string and the pipe-to-bore annulus surrounding the same; and for the purpose of flushing or retrieving drilled chips from the bottom of the well bore. A limiting factor in such drilling operations has been the singular fluid circuit, either the pressured (downward) circulation of mud or the reverse (upward) vacuum circulation of air; and also a limiting factor is the operation of singular drilling strings in such well bores. It is a general object therefore, to provide a new drill rig drive and coaxial drill strings for the circulation of separate fluids and for the operation of separate drilling tools. With the present invention there is a drive at the head of a multiplicity of concentric drill pipes and between which there are annuli for conducting separate columns of fluid, each drill pipe being independently capable of operating a well drilling or servicing tool such as a bit or reamer.
Drill string drives have been carried by drilling rigs to move relative thereto at the uppermost end of the drilling string operated thereby. To these drives there have been various fluid attachments, such as a rotary hose attachment through a swivel, and to the end that there is fluid column (singular) communication through the inner diameter of the drill string. This invention involves a multiplicity of drill strings and a plurality of separate fluid circuits to well tools and servicing means at the bottom of the drill string, it being an object to provide a driving head at the top of said multiplicity of drill strings to revolve the same in manifold communication with fluid pressure sources and through separate fluid circuits. With the present invention there is a multiplicity of concentric drill pipes, for example four drill pipes, coaxially driven together with annuli therebetween so as to conduct separate columns of fluid coextensively therethrough, there being a swivel-manifold for supplying and withdrawing fluid from the top ends of the drill pipe annuli respectively.
Singular drilling tools have been restrictively operated by drill strings at or near the bottom of the well bore being dug; and dependent upon singular fluid circulation. It is an object of this invention to provide for the simultaneous operation of a plurality of drilling tools by means of separate and distinct drill strings; and with independent fluid circulation therethrough as circumstances require. With the present invention, any one of the multiplicity of drill strings or pipes can be employed to operate a drilling tool and/or employed to deploy or retrieve fluids employed to best advantage in the drilling operation.
Drilling operations become involved with collapsing geological formations etc., and ultimately there is the withdrawal of the drill string and its replacement with well casing. It is an object of this invention to provide for the conversion of a drill string into a well casing, and for the independent withdrawal of the other drill string or strings. With the present invention, the multiplicity of drill strings can be disconnected or interconnected one from the other, so that both simultaneous operation and independent removal from the well bore is feasible.
The multiple drill string drive of the present invention not only operates a multiplicity of drill pipes, but conducts separate columns of fluid through the annuli therebetween. It is an object therefore to provide equalibrium in an anti-friction drive that simultaneously rotates the multiplicity of drill pipes, and to assemble sections thereof in concentric relation so as to be handled with facility as units. A feature of this invention is the uniform inside and outside diameters of the drill pipes with anti-spread means at the threaded pin and box couplings thereof. And in accordance with this invention, the multiplicity of drill pipes are assembled into sections with spreader means so as to ensure concentricity and also to provide the said assembly thereof when circumstances require.
It is also an object of this invention to correlate the foregoing general objectives as they are embodied primarily in a "Top Head Drive" of extreme rugedness adapted to separately conduct liquids at high pressure and gaseous fluids at high vacuum through the annuli between the multiplicity of drill pipes. There is a unique balance of drive means that transmits torque into the drill strings, in such a manner that complete control is attained over direction of rotation, speed and power to be applied. And, despite the ultimate power that is available through this "Top Head Drive", the drilling rig required for its operation is devoid of complexity and/or over-structure, and all to the end that portability into otherwise inaccessible drilling locations is made possible.